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Abstract

(NH) temperature in the last millennium based on multy proxy records depict small-amplitude variations followed by a clear warming trend in the last two centuries. We use a coupled atmosphere-ocean model simulation of the last 1000 years as a surrogate climate to test the skill of these methods, particularly at multidecadal and centennial timescales. Idealized proxy records are represented by simulated grid-point temperature, degraded with statistical noise. The centennial variability of the NH temperature is underestimated by the regression-based methods applied here, suggesting that past variations may have been at least a factor of two larger than indicated by empirical reconstructions. Reconstruction of past climate from palaeoclimate proxy data is important for detection of anthropogenic climate change. A